


When The Nightingale Sings

by Sanjuno



Series: Ideas of March 2018 [10]
Category: Katekyou Hitman Reborn!
Genre: Alternate Universe - Dragons, BAMF Sawada Tsunayoshi, Beware the Dragons, For you are flammable, Gen, Gotta Love that Atavism, Other, Possessive Skies, Reborn was not prepared for this to be a thing, The Guardians are their Hoards, The Skies are the Dragons, Welcome to the Godzilla Threshold, because aliens
Language: English
Status: Completed
Published: 2018-08-26
Updated: 2018-08-26
Packaged: 2019-07-02 14:41:10
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,323
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15798624
Author URL: https://archiveofourown.org/users/Sanjuno/pseuds/Sanjuno
Summary: The problem with crossbreeding compatible species is that you have no idea what sort of throwback traits and mutations the resultant hybrids are going to display.Those with access to the Flames of Dying Will all have a bit ofOtherin their ancestry. Something that is both more and less than Human, and Skies are theleastHuman of all the Flame Types.Putting a Sky under a Seal puts their Flames under pressure. Like the Nightingale in a cage who refuses to sing, a Sky under a Seal suffers in silence...... until that sealbreaks, and the Sky roars to cast the heavens down.





	When The Nightingale Sings

**Author's Note:**

  * For [dogsanddigimon](https://archiveofourown.org/gifts?recipient=dogsanddigimon).



> Tsuna is a complete selfish _brat_ of a child when we meet him in canon and now he's 100% owning that. 
> 
> Reborn's karma has come 'round to kick him in the teeth and it's glorious. ♥

=/=

It was impossible to hide a Sky when they manifested, given the way they were immediately encased in an indestructible crystalline eggshell that glittered and shone with a thousand shades of the Rainbow.

There was some debate, in the Alliance, over which Sky had cracked their shell at the youngest age. Xanxus di Vongola had already manifested and learned how to control his Flames when he was taken in off the streets at eight. Still, some of the Giglio Nero Donna’s had Manifested that young before as well. Discounting them just because they were women, or because they often went on to become the Sky Arcobaleno of their generation was foolishness. Reborn’s charming Aria had cracked her shell before puberty, and he was very proud of her strength.

Reborn glared at the pathetic excuse for a personality profile that Bakamitsu had dropped into his hands and wondered what the gossips would say if they learned the Young Lion’s spawn had cracked his shell at  _four_.

/.../

Reborn had not quite known what to expect when he arrived in Namimori to teach Sawada Tsunayoshi the laws and customs of his father’s culture. The CEDEF report had listed Tsuna as easily distracted, high-strung, shy, and constantly anxious. Whatever quality of student Reborn  _had_  thought to expect, it was nothing like this.

A young Misty Cloud with Fon’s face was snarling at him, with a smallish army of lesser Flames following his lead. The baby Sky that Reborn had come halfway around the world to teach was all-but smothered in the arms of two girls. A brightly coloured Sunny Mist and a dark haired, sloe-eyed Misty Lightning that clung to their Sky with all the ferocity of a protective mother cat. Just in front of the huddle a Misty Rain bounced a sword against his shoulder, smiling like a natural hitman, and a Misty Sun cracked his wrapped knuckles with a shining grin, both with hints of Lightning crackling through them. Behind the main cluster a Stormy Cloud stood with her feet planted and arms crossed, scowl firmly on her face as she glared at Reborn. She was the only one bound directly to the Sky without a hint of Mist in her, and was clearly calculating how far she could punt him.

This was bad. None of the children were a threat to him, not even if they all banded together. No, the problem here was that Reborn was no good with unanchored Mist-magnets. Although he _was_  going to look into what _exactly_ had made his new student so determined to hide from reality. The investigation was something that would have to wait. Right now Reborn needed a way to get his new student to focus on the world around him without drifting back into the Dreaming that a Sky with too many Mist bonds was prone to.

What to do?

Hm. Perhaps Reborn should try going the  _traditional_  route. The Japanese liked tradition, right?

Now, who did Reborn know that would be a shiny enough distraction for a Sky of Tsuna’s potential strength?

... Ah. Yes, that would do nicely.

/.../

At first Reborn had debated dropping the bait in front of Tsuna in class, but as hilarious as that might have been at another time,  _nothing_  Tsuna had done so far was in any way predictable. As much as Reborn was enjoying both the chaos that followed his new student and the challenge of figuring out Namimori’s secrets, Reborn would never risk  _actually_  breaking Omertà.

So Reborn decided to do some creative editing with his first idea and rewrote the scene he had initially had in mind for maximum shock value.

/.../

At first Tsuna had no idea what to make of his new home tutor. Reborn was tiny as an infant but was actually older than Tsuna’s parents and the first thing Reborn had tried to do was  _shoot him in the head_  and if Kyouya-sempai had been even a  _little_  bit slower... well.

Tsuna shuddered and hugged himself. It did not bear thinking about.

Reborn insisted that the bullets would _not_ have killed him, but Tsuna really,  _really_  did not want to be shot. Not even non-fatally. _Especially_ not by someone who was visibly plotting messy murder every time Tsuna’s dad came up in the conversation.

Sure, Reborn was better about treating Tsuna fairly now that they had gotten to know each other a bit better, but Tsuna still could not shake the feeling that if Tsuna had been a disappointing student Reborn would have taken his dislike for Iemitsu out of  _Tsuna’s_  hide. Which was a terrible thought and Tsuna quickly strove to forget that the idea had ever occurred to him.

What was strange and also worrisome to consider was that Reborn was apparently here as a  _favour_  for Tsuna’s father. Why Reborn was doing a favour for a man he visibly and verbally disdained was a question Tsuna was not certain he wanted answered.

If Tsuna got too nosy then Reborn might stop being polite about  _Tsuna’s_  secrets, and Tsuna’s secrets were not just about him. So Tsuna was content to let the unspoken truce hold for as long as he could get away with his silence.

“Let’s go, Tsuna.” Reborn toddled cheerfully towards the park, and Tsuna felt a sudden chill when he realized that all of his treasures were nowhere nearby. “We have a meeting.”

“Wait, Reborn!” Someone less than two feet tall should  _not_  be capable of dragging four times their own bodyweight down the street. This was unfair. Tsuna squeaked as he tripped and scrambled to stay upright. “What meeting?”

"A personal meeting.” Dark eyes gleamed from under the shade of his fedora, and Reborn smirked before letting Tsuna go, content to let his student walk under his own power. “Watch and learn something, Dame-Tsuna.”

/.../

There was a slim figure lounging in the shade of a sakura tree, dapples of light catching on silver chains and coloured stones. A slender hand lifted in polite greeting. “Reborn.”

“Smoking Bomb.” Reborn hopped down off Tsuna’s shoulder to approach the younger hitman. Normally Reborn liked to work his students into a frenzy for the first few months to teach them how to think through their initial instinct to panic, but Tsuna was the type to need plain statements. So while the idea all but gave Reborn hives, he was going to show his silly student that someone Tsuna’s own age could earn and keep respect in their world  _before_  he started training Tsuna to fight. “You made good time.”

“You made me an offer worthy of a little extra effort.” Stepping out into the light, the explosive expert’s narrowed green eyes raked over Tsuna with clear interest. “A new student?”

“You see now why I asked for speed.” Reborn hid his triumph as the bomber hummed absently and handed over the information Reborn had asked him to gather. Pulling the strings to get Shamal’s protégé to come to Namimori personally had been worth it, especially since Reborn had taken the calculated risk of not mentioning he was tutoring a Sky. The Smoking Bomb was clearly interested in Tsuna despite managing to stay entirely professional. That fact was almost secondary to the report the younger hitman had put together on the state of the Alliance and a bluntly analytical profile on Sawada Iemitsu.  _This_  was the kind of report Reborn had been expecting from the CEDEF. “Hm. You do good work, Smoking Bomb. The money will be in your account by tonight, and I will ask my daughter if she would like to meet with your sister.”

“It’s appreciated, Reborn.” Business concluded, there were no reasons to linger and every reason to leave, but the silver haired teen hesitated. Just as Reborn had expected he would. The silence stretched just a bit too long as Smoking Bomb stared at Reborn’s student with intent eyes. Finally, the younger hitman shook his head. “The name is Gokudera Hayato, called the Smoking Bomb. It was… nice to meet you, _sora-dono_. I work freelance, so if you need a job done Reborn can put you in touch with me. Ciao.”

Inclining his head in a quick acknowledgement, the silver haired teen moved to depart before he further embarrassed himself over Sky Attraction. Reborn saw the regret sear itself across Tsuna’s face as the Bomber made to leave and made the shot.

_Bang!_

Gokudera whirled around, face slack with horror as the Sky crumpled.

One knee on the ground, Tsuna’s hand closed around the bomber’s wrist. Gokudera froze in place with his arms still out to catch the other boy. 

Reborn peered up at his student in confusion. Tsuna had been oddly quiet since the first time Gokudera had spoken, and now that he had finally managed to hit Tsuna with the special bullet Reborn had been expecting more in the way of ardent declarations. There were no Flames, and Tsuna’s clothes had remained intact. Instead of Hyper Dying Will mode, Tsuna was giving off the impression of a sealed pot set to boil, building pressure that was about to...

**_BOOM!!_ **

... explode. On his back in the bushes several meters from where he had been standing, Reborn blinked rapidly as his ears rang in the aftermath of Tsuna going up like a small atom bomb made of Flames. Ow.

/.../

_Mine_. 

Rusted chains falling away, too-small cage finally broken open. 

_Mine_.

Free for the first time since his father and the old man had tried to damp his inner fire.

_Mine_.

His heart beating all out of rhythm as he scrambled to catch the fragile treasure fallen into his grasp without causing damage. Something precious and unique, old hurts gleaming silver and gold where the scars had healed over.

“Mine.” Tsuna curled in on himself, wanting to gather his new treasure close but terrified of sending shattered pieces scattering into dust. “Please?”

Sprawled out in the gentle cradle of Tsuna’s paws, Gokudera was a crimson opal, fractals of violet-blue-green-gold flaring within scarlet, a Storm of brilliant colours against the amber of Tsuna’s claws. “... Eh?”

“Please?” A whine was building in Tsuna’s throat. How was he supposed to ask? His other treasures had  _always_  been his. They had helped Tsuna chip away at the fetters his father had laid on Tsuna’s inner fire. They had been there to help despite Tsuna being crippled and weak. He was supposed to defend his hoard, but they defended Tsuna too. Tsuna had the very _best_ hoard, and he had never before considered wanting  _more_  but... “Mine.”

“... my Sky is a UMA?” Pale, scarred fingers pressing against Tsuna’s muzzle, patting gently like his pretty treasure thought Tsuna might reject the touch. The silver haired teen was mumbling in strange tongues even as he relaxed into the Harmony Tsuna offered, touch growing more sure as Tsuna pulled Gokudera closer. 

Rumbling happily, Tsuna coiled up around the newest member of his hoard and simply basked smugly in his triumph. Tsuna had the  _best_  hoard. He bet nobody else had a treasure with  _five_  colours. Ha!

/.../

Up a nearby tree and not planning to climb down any time soon, Reborn stared in utter shock as the giant supernatural lizard that was supposed to be his student cuddled the Hurricane of Flames most of the gossip painted as too complicated and volatile to ever properly bond with a Sky. Well, Tsuna was happily proving them wrong, even if he  _did_  currently look like something that belonged in an illuminated book of fairy tales.

This was _surreal_. Reborn had not been this badly shocked since the Fated Day when he had gone from a full-grown man in his prime to an infant. People were not supposed to turn into dragons. Dragons were make-believe! Sure, Skies hatched from eggs when they woke their Flames and they were jealous of their Guardian’s attention and tended to collect large amounts of wealth, but... yeah.

Never mind, Reborn was not even capable of convincing  _himself_  that this was impossible. Flames always had broken the laws of physics. What was one more thing on the list? 

What the hell had caused the transformation though? Reborn had shot other Skies with the special bullets, and none of  _them_  had  _physically_  transformed into dragons. What was different about Tsuna? What the  _fuck else_  had Bakamitsu left out of his report?

/.../

Half a world away, an old man ruled his Family with a kind smile and an iron Will. He hoped Reborn took to young Tsunayoshi as well as he had favoured the young Cavallone heir.

While it was regrettable that Timoteo had needed to Seal the child back then, at the time it had been for the greater good of the Famiglia. A young Sky born to Primo’s line being that pure and that _strong_ would have attracted far too much attention and destabilized the succession. The situation with Xanxus had been bad enough, and the Ninth as still dealing with the fallout from the public backlash of claiming the boy as his blood even sixteen years later. 

Still, Reborn would be able to teach Tsunayoshi enough to get by as the new Heir despite the Seal. It was a moot point anyway. Hyper Dying Will mode would break the Seal on Tsunayoshi’s Flames, and Reborn would be able to claim the credit for the boy’s eventual strength.

After all, the only ones who knew Tsunayoshi had woken his Flames once before were Iemitsu and himself, and Iemitsu knew better than to spread that information around. Sealed or latent, who would be able to tell after Tsunayoshi was Active without knowing that little fact? It would all work out for the better this way.

/.../

Under the Iron Fort, a glacier strung with chains sat in the centre of the darkened catacombs. The ice shuddered, cracked.

Shattered. 

Ice vanished into steam as a nightmare of blood-amber scales unfurled massive wings with a scream of enraged triumph.

=/=

**Author's Note:**

> So it turns out that sealing a sky equals dragons when the seal goes away! The More You Know. Welcome to the Godzilla Threshold, Timoteo. *blows kisses*
> 
> For the original prompt from tumblr dogsanddigimon asked: " _This started as a joke, but Dragon!Skies_


End file.
